Device for the production of tubular bags

ABSTRACT

A device for producing tubular bags filled with bulk goods from continuous foil tubes. The device includes a pair of sealing tools that seal or weld the foil tubes in bag-length intervals. A pair of closing bars connected to the sealing tools are biased toward each other and press the foil tubes before the sealing tools are closed. A stripper is provided to remove the residue of the bulk goods from the area of the seal by a wiping motion in the direction of bag movement through the device. The closing bars are connected to the stripper so that through a closing movement of the closing bars, the stripper is pulled along in the run direction of the foil while touching the foil to strip the area to be sealed before the sealing tools close.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of, and claims the benefit of the filing date of,U.S. patent application Ser. No. 10/292,679, filed on Nov. 12, 2002 nowU.S. Pat. No. 7,069,709, entitled Device For the Production Of TubularBags, which is a continuation of U.S. patent application Ser. No.09/610,980, filed on Jul. 6, 2000, entitled Device For the Production OfTubular Bags, which issued as U.S. Pat. No. 6,519,922 on Feb. 18, 2003.

BACKGROUND

During the packing of pourable, but somewhat bulky, products in foiltubular bags, the products have a tendency to bridge across the bagthereby clogging the bag. This can occur frequently as the bags arebeing filled. As a result, care has to be taken as the bags are beingsealed to ensure that pieces of the bulk goods do not remain hanging inthe region of the tubular bag being sealed. Bags are typically seated ata seam between a pair of sealer jaws or tools. It is important to ensurethat crumbly products and pieces do not remain hanging in the area ofthe sealed seam due to uncontrolled fall-in. Potato chips because oftheir low specific weight are a typical example of a troublesomeproduct.

Even with very precise metering, due to the varying character of theproduct, pieces of the product filling the bag can float or remainhanging in the area of the seal at the moment that the sealing toolsseal or close. If these pieces of product or bulk goods are sealed inthe region of the seam, then the bag may remain open or seal in anunattractive fashion so as to be unsaleable.

In a typical bag producing device, the welding or sealing tools aremounted on pairs on rotating axles. The axles are positioned on bothsides of the tubular foil and turn the sealing tools synchronously insuch a way and at a rotational speed such that the opposing sealingtools meet each other after they pass the length of a bag. After meetingon opposing sides of the foil, a pair of tools travel straight togethera short distance with the foil. The bag is subsequently sealed with asecond pair of tools attached to the opposite side of the axles (i.e.the tools are offset 180 degrees).

Conventional seal tools typically have an associated closing bar thatpresses the tubular foil together. The seal tools also may include astripper mounted on the turning axles, ensuring that the foil is pressedtogether and stripped before the sealing tools meet each other. The foilis thus prepared for the sealing process and at the same time, fall-inof the bulk goods into the area of the seal is prevented. The stripperremoves the residue of the bulk goods on the inside of the tubular foilfrom the region of the seam.

European Patent Application 666215 A1 discloses a bag closing device inwhich the closing bars and the bar-shaped strippers are mounted on asupport plate next to the support for the sealing tools and at a rightangle to the foil passing through. The closing bars and the bar-shapedstripper swivel on their supports and are spring-loaded so that they canpress the foil together as well as stripping the residue of the bulkgoods from the area of the seal with a wiping motion.

To protect the welded tubular bags from the hot sealing tools, EPA666215 A1 discloses wing-like shields attached to the bars andpositioned between the just-sealed bag and the sealing tools. Theclosing bars serve as strippers, and are moved by the driveshafts. Inorder to ensure that the sealing tools press the tubular foil togetherand heat it for the time necessary for sealing, the tools are attachedso that they are axially movable and are loaded with compressionsprings. The circular movement of the sealing tools is modified into astraight line during the sealing segment. One full rotation of the axlesthat support the sealing tools produces two sealing processes.

The disclosed device has several disadvantages. The attachment andbearing of the necessary components makes installation difficult,requires space, and makes the device sluggish in its movements, therebyalso reducing the clock rate of the packing device. Furthermore, becausethe rotating movement cycles and movement axes can only be positionedopposite to one another in a limited way, the effective zones of theclosing bars and the strippers are restricted to a limited area.

The sealing device disclosed in U.S. Pat. No. 4,663,917 operates in asimilar manner. German Patent Application No. DE 400 50 078 discloses asealing device in which the closing bars are attached to the sealingheads directly using springs. The foil on both sides of the sealingtools or jaws is pressed together by the spring-loaded closing bars. Astripping motion is not provided in this design.

The device disclosed in German Patent Application No. DE 24 01 800 doesuse a stripper, but the stripper only functions as the closing barsdescribed above. A direct connection and movement of this component withthe sealing tool in the sense of a stripping movement is not given.

Thus, there remains a need for a bag producing device that includesclosing bars and strippers positioned directly on the sealing tool orthe tool mount, that provides for movement of these elements so that asecure operating cycle is produced at a high clock frequency.

SUMMARY OF THE INVENTION

According to the present invention a device for the production oftubular bags filled with bulk goods from a continuous foil tube movingin a run direction is provided. The device may include a pair of sealingtools that seal the foil tube in bag-length intervals; a pair of closingbars provided for the tools and directly clamped to the sealing tools,each closing bar biased toward the other closing bar for pressing thefoil tube before the sealing tools are closed; and a stripper, which cantouch the foil tube, through which the residue of the bulk goods can beremoved from the area of the seal by a wiping motion effective in therun direction. The closing bars may be connected to the stripper so thatthrough a closing movement of the closing bars, the stripper is pulledalong in the run direction while touching the foil before the sealingtools close.

Preferably, the closing bars are connected to support bars which passthrough clamps positioned on the sealing tools and wherein each supportbar is loaded against the closing movement of the sealing tools by areturn spring. The stripper may be connected to the sealing tools sothat the stripper is pulled by the movement of the support bars againstthe force of the springs in a swinging movement while touching the foil,out of the area where the sealing tools touch the foil. The swingingmovement of the stripper typically covers a distance at least threetimes greater than the distance moved by the support bars. The movementof the support bar is mechanically transmitted to the stripper by apositioner attached to the sealing tool. The positioner may include atracer pin and the support bar may have a slanted surface positioned tocontact an end of the tracer pin.

In an alternative embodiment, the present invention may include a devicefor the production of tubular bags filled with bulk goods from acontinuous foil tube moving through the device. The device may include apair of moveable sealing tools positioned on opposite sides of the foiltube, the sealing tools configured to come together to seal the tube.Each sealing tube may include a closing bar biased toward the closingbar on the opposing sealing tool and adapted to move with the sealingtool to contact the tube; a sealing jaw positioned opposite the sealingjaw on the opposing sealing tool so that when the sealing tools cometogether the sealing jaws contact the tube to thereby seal the tube; anda stripper located downstream from the closing bar in the direction ofmovement of the foil tube and being configured to move along the tube inthe direction the tube is moving to strip the bulk goods away from thearea of the tube to be sealed at the same time that the sealing jaw ismoving toward the tube.

The closing bars may move in a direction generally perpendicular to thedirection of movement of the tube and are biased toward each other by aspring. Each sealing tool may further comprise a support bar connectedto the closing bar and aligned in the direction of movement of theclosing bar. The support bar may be configured to move in a directiongenerally perpendicular to the movement of the tube against the bias onthe closing tube.

The stripper may include a stripper bar. The stripper bar may beconnected to the closing bar so that movement of the closing bar causesmovement of the stripper bar along the tube in the direction the tube ismoving. A tracer pin may be provided so that when the support bar movesthe motion of the support bar is transferred to the stripper through thepin. The end of the support bar adjacent the pin may include a taperedsurface so that as the end of the support bar moves away from the tubethe tapered surface slides along an end of the pin to thereby force thepin to move in a longitudinal direction. The pin is generally positionedbetween the support bar and the stripper so that when the pin is forcedto move in the longitudinal direction by the support bar the other endof the pin contacts the stripper to cause the stripper to move along thesurface of the foil away from the sealing jaws and the area of the foilto be sealed.

The stripper bar may be connected to a mechanical linkage pivotallymounted to the sealing tool. The tracer pin may be positioned betweenthe support bar and the mechanical linkage so that linear movement ofthe support bar is translated to swinging movement of the mechanicallinkage.

It is to be understood that both the foregoing general description andfollowing detailed description are exemplary and explanatory only, andare not restrictive of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, as aspects, and advantages of the presentinvention will become apparent from the following description, appendedclaims, and the accompanying exemplary embodiment shown in the drawings,which are briefly described below.

FIG. 1 is a schematic representation of a bag producing device of thepresent invention.

FIG. 2 is a front view in elevation of the device of FIG. 1 with opensealing jaws or tools, and a filled tubular bag running between them.

FIG. 3 is the front view of FIG. 2, in which the sealing jaws are aboutto close.

DETAILED DESCRIPTION

Although references are made below to directions, such as left, right,up, down, etc., in describing the drawings, they are made relative tothe drawings (as normally viewed) for convenience. These directions arenot intended to be taken literally or limit the present invention in anyform. Identical or similar components have the same reference number inall figures.

The present invention is directed to a device for the production oftubular bags filled with bulk goods and similar items. The deviceproduces bags from continuously running foil tubes using sealing tools.The sealing tools typically include tool pairs that seal and/or weld thefoil tubes at bag-length intervals. The device may also include pairs ofclosing bars which press the foil tubes flat before sealing. Moreparticularly, the present invention is directed to a device in which apair of strippers supplement the closing bars by contacting the foiltube and removing the residue of the bulk goods from the area of thetube to be sealed by a wiping motion in the run direction before theapplication of the sealing tools.

According to the invention, this is achieved by clamping the closingbars, which can be laid against the foil, directly to the sealing toolsor their supports, respectively, in such a way that they are pressedagainst the foil by the closing movement of the sealing tools prior tosame while tensioning a return spring. The closing bars may be connectedto the strippers in such a way that through their closing motion, withthe stripper touching the foil, the strippers are pulled along in therun direction before the sealing tools close.

It is particularly advantageous to connect the closing bars with thestrippers, which are positioned downstream in the run direction, sothat, by means of the tension movement produced against the returnspring or something similar, with the movement of the sealing tools, thestrippers are pulled along in the run direction while touching the foilbefore the sealing tools close.

It is advantageous to attach the bearings or clamps of the closing barswith spring loading to the supports of the sealing tools. With theclosing movement of the sealing jaws, the closing bars are positionedagainst the foil and press it flat. The support bars are thereby movedagainst the power of a spring after the application of the closing bars.This movement is transmitted to the bars serving as strippers. Thestrippers are moved with the closing movement of the sealing tools inthe fill direction, while touching the foil, thereby removing theresidue of the bulk goods positioned inside the foil tube from the areaof the seal.

An exemplary embodiment will be described and its mode of operation willbe explained with reference to the drawings.

FIG. 1 shows both tool mounts 1 and 2, moved by a drive or crank 16(shown in FIG. 2) in which the sealing jaws 3 and 4 are attached. Clamps5 are attached in pairs on each of the tool mounts 1, 2, which clamp andguide support bars 6. The support bars 6 are clamped or connected to theclosing bars 7 at their front ends. In the clamp 5, the support bars 6are loaded with the return spring 8. If the tool mounts are movedagainst each other to seal the tubular bag, the closing bars 7 meet eachother, including the tubular foil which is not shown, and push thesupport bars 6 through the clamp 5 against the return power of thespring 8 to the rear away from the tubular foil.

The rear ends of the support bars 6, or additional components attachedto them, include slanted surfaces 9. The tracer pins 10 put into thetool mount 1, 2 contact the slanted surfaces 9. The tracer pins 10 presson a portion of the linkage 11 with their lower end.

The linkage 11 is connected to the bar 12 which acts as a stripper. Forreasons of clarity, the linkage 11 in FIG. 1 is only depicted once andonly schematically. Naturally, each of the tracer pins 10 and stripperbars 12 has a corresponding linkage 11. The linkage 11 is clamped to thetool mounts 1, 2 and pivotally mounted in the bearings 13 in such a waythat the movement of the tracer pin 10 produced by the slanted surface 9is mechanically translated in such a way that the bars 12 touching thefoil move downward from the region between the sealing jaws 3, 4 beforethe jaws close.

Any possible residue of the bulk goods remaining on the internal wall ofthe foil is wiped off by this movement of the bars 12. The sealingsurfaces of the foil are thus free from the residue of the bulk goods.The mechanical translation shown is typically arranged so that motion ofthe support bar produces three times as much motion of the stripper bar12. The ratio of motion may be larger than three or, if necessary, canbe aided by means of supplementary devices with compressed air.

FIG. 2 shows a sealing tool in an open position, in which the tubularbag 14 can be filled with bulk goods 15. The tool mounts 1, 2 with thesealing jaws 3, 4 are positioned on cranks 16 equipped with returnelements in such a way that when the cranks are turned the position ofthe sealing jaws 3, 4 is always directed toward each other and therebyalso against the tubular foil 14.

When the closing bars 7 meet each other during a closing movement of thesealing jaws 3, 4, the support bars 6 are thus moved to the rear againstthe return power of spring 8. The tracer pins 10 are pressed downwardsby the slanted surfaces 9. As shown in FIG. 3, the stripper bars 12 arepulled away downwards by the linkage or lever arm 11 before the sealingjaws 3, 4 meet each other. Any residue of the bulk goods 15 that mayremain in the area of the seal is thereby wiped off. A spring 17 may beincluded to provide the force necessary to return the linkage 11 andstripper bars 12 to their original positions. The spring 17 may bereplaced by a drive or a counterweight on the lever arm 11.

The embodiment shown has the advantage not only that the tool mounts 1,2 with the sealing tools 3, 4 are only required to perform a smallcircular parallel movement, but also that the necessary energy supplyand control equipment operate without a winding effect and withoutrotary joints. By mounting the closing bars 7 and stripper 12 on thetool mounts 1, 2, these components can operate without expensive, heavy,and therefore sluggish components, which makes operation of the packingmachine at a high clock frequency considerably easier.

Through having the design form of the closing bars in direct contact tothe sealing tool and detached from a rotating tool mount, the devicedescribed according to the invention is also suitable for packingdevices in which intermittent operation with individually suppliedpackaging units is performed instead of a continuously running foiltube.

The priority documents, European Patent Application 00112492.4 filedJun. 13, 2000 and German Patent Application 299 11 847.9 filed Jul. 7,1999, are hereby incorporated by reference herein.

Given the disclosure of the present invention, one versed in the artwould appreciate that there may be other embodiments and modificationswithin the scope and spirit of the invention. Accordingly, allmodifications attainable by one versed in the art from the presentdisclosure within the scope and spirit of the invention are to beincluded as further embodiments of the present invention. The scope ofthe present invention is to be defined as set forth in the followingclaims.

1. A device for the production of tubular bags filled with bulk goodsfrom a continuous foil tube moving in a run direction comprising: atleast a pair of tool mounts that follow an orbital movement, wherein thetool mounts have a near end and a distal end, and wherein the near endis linked to a device that imparts the orbital movement to the toolmounts; a first pair of opposing tools, each mounted on one of the pairof tool mounts, that cyclically engage the tube and seal the foil tubein bag-length intervals during a portion of the orbital movement; asecond pair of opposing tools, each mounted on one of the pair of toolmounts, that remove bulk goods from the area of the seal by a wipingmotion effective in the run direction, linked to follow a pathresponsive to the orbital path; and a pair of opposing passive devices,each mounted near the distal end of each tool mount effective during atleast part of the portion of the orbital movement, wherein the passivedevice affects the path of a selected pair of the first and second pairsof tools mounted on a carrier such that the distal end of the selectedpair follows a path parallel to a path the near end of the selected pairfollows, wherein the pair of passive devices includes a tracer pin. 2.The apparatus of claim 1, wherein the pair of passive devices iseffective during at least all of the portion of the orbital movement. 3.The apparatus of claim 1, wherein the pair of passive devices iseffective during at least the time the tube is engaged.
 4. The apparatusof claim 1, wherein the pair of passive devices is linked to the secondpair of opposing tools.
 5. The apparatus of claim 1, further comprisinga second pair of opposing passive devices, each mounted near the nearend of each carrier, effective during at least part of the portion ofthe orbital movement, wherein the second pair of passive devices affectsthe path of the second pair of tools mounted on the carrier.
 6. Theapparatus of claim 1, further comprising a second pair of tool mounts,each having tools mounted thereon as did the first pair of tool mounts.